They are called striations and they occur on the planchet strip while the strip is being fed (or pulled) through the blanking press. They occur primarily on cn clad coins and can be quite dramatic or nearly impersceptible. They always run in the same direction on the coin which is what points to a problem on the cn clad strip. I've seen them on IKE's, Kennedy's and Washington Quarters. I've not seen any on Roosevelts or Jeffersons.
